The present invention relates to an improved firearm sight, and particularly to the combination of a shoulder-fired gun and an improved optical sight that is easily adjustable by the shooter for corrected ranges after observing previous target misses due to incorrect range settings, without removing the eye from the target or sight.
The invention is particularly useful in the "area fire" mode in which an explosive shell is projected to the immediate area of the target, such as a prone man, and exploded in air over the target by a time fuze carried by the shell.
Range-adjustable sights are, of course, well known in the art. Most of these involve the combination of a fixed front sight with a vertically-adjustable rear sight, as in Everitt U.S. Pat. No. 2,871,566, for example.
Steck U.S. Pat. No. 3,645,635 discloses a collimating sight comprising a rod of fluorescent material mounted in a tubular holder for pivotal movement about the rear end of the holder in a housing. Light from the target passes through the rod, which provides a reticle and is reflected by a first mirror onto a half-reflecting second mirror, where the reticle image is viewed superposed on the target image. The range is adjusted by pivoting the rod vertically, by means of an adjusting screw, which changes the angle between the rod axis and the gun bore on which the sight is mounted.
In accordance with one aspect of the present invention, a collimating sight of the type disclosed in Steck U.S. Pat. No. 3,645,635 is improved by substituting, for the adjusting screw of Steck, a range knob mounted on the firearm near the trigger and operatively connected to the rod holder, as by a rack and pinion gear combination, and mounting a range scale on either the second mirror or the reticle holder and a fiducial marker on the other, whereby the firearm can be used against a visible target by: (1) estimating the range to the target; (2) setting the range knob to this range while observing the relative positions of the marker image on the scale, or the scale image on the marker; (3) aiming and firing the firearm at the target; (4) visually observing the location of the shot relative to the target; (5) resetting the range knob to a corrected range; and re-aiming and re-firing at the target.
In a preferred embodiment, incorporating explosive shells to be exploded in air over the target, the invention further involves coupling to the range knob a variable resistance, e.g. a potentiometer, connected to a firing delay circuit in the explosive shell, whereby adjustment of the range knob to a particular range on the range scale also adjusts the time of the delay circuit to the same range.